higher biology
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Re: higher biologyoh D: some teacher said they're noramlly unit1&3 and rarely 2 but it could still happen?(Original post by Alt__x)
That's not true they could be about any of the three units, last year we had one about osmoregualtion in fish which was a gift
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oh dear god noooooooooooo!!!!! i hate osmoregulation in fish... it's the one thing i literally cannot get my head around
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Re: higher biologyUnit 3 not too bad... Although unit 1 has more to write about I think..(Original post by TheFOMaster)
This year will have Unit 3 for sure because years was Units 1 and 2. I really hope Unit 1 comes up though cause thats definitely my strongest point. -
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Re: higher biologyUnit 3 is ok... Unit 2 is really bad though. Also we had a teacher swap midway cause my teach went on maternity leave, So the 2 classes were taught in a class of 34 by 1 teacher from mid Unit 2 to the beginning of Unit 3 so its all shaky around there.(Original post by Imfeelingthis)
Unit 3 not too bad... Although unit 1 has more to write about I think.. -
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Re: higher biologyI was hoping osmoregulation would be up this year, but since it was up last year it probably won't be.(Original post by Alt__x)
That's not true they could be about any of the three units, last year we had one about osmoregualtion in fish which was a gift
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Re: higher biologyAahh that happened with us for english.. We went 4 weeks without an English teacher(Original post by TheFOMaster)
Unit 3 is ok... Unit 2 is really bad though. Also we had a teacher swap midway cause my teach went on maternity leave, So the 2 classes were taught in a class of 34 by 1 teacher from mid Unit 2 to the beginning of Unit 3 so its all shaky around there. hmm parts of unit 3 is a bit of common sense really I think
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Re: higher biologyOur teacher gave us a list of essays we could be asked for all 3 units. If you know these you'll be fine:
Essay Practice
Essay 1: Give an account of the movement of materials across the plasma under the following headings: 1. diffusion and osmosis, 2. active transport and 3. endocytosis and exocytosis.
Essay 2: Give an account of the role of light and photosynthetic pigments in photosynthesis.
Essay 3: Give an account of the light-dependent stage of photosynthesis.
Essay 4: Give an account of the Calvin cycle.
Essay 5: Give an account of celular respiration under the following headings: 1. glycolysis, 2. krebs cycle and 3. the cytochrome system.
Essay 6: Give an account of the structure and replication of DNA.
Essay 7: Give an account of protein synthesis under the following headings: 1. transcription and 2. translation.
Essay 8: Give an account of the structure and function of polypeptide chains found in proteins.
Essay 9: Give an account of the stucture and replication of viruses.
Essay 10: Give an account of cellular mechanisms under the following headings: 1. phagocytosis, 2. production of antibodies and 3. production of compounds.
Essay 11: Write notes on high speed evolution each of the following: 1. the peppered moth, 2. antibiotic resistance in bacteria and 3 heavy metal tolerance in grasses.
Essay 12: Give an account of how a new species arises through speciation and adaptive radiation.
Essay 13: Give an account of the production of new varieties of organisms under the following headings: 1. genetic engineering and 2. somatic fusion.
Essay 14: Explain the osmotic problems of freshwater fish and describe the adaptions such fishes possess to maitain water balance.
Essay 15: Explain the osmotic problems of saltwater fish and describe the adaptions such fishes possess to maitain water balance.
Essay 16: Give an account of how intrasecific competition in animals can be reduced.
Essay 17: Using named examples give an account of defense mechanisms in plants under the following headings: 1. structural defence mechanisms and 2. the ability to tolerate grazing.
Essay 18: Give an account of how plants grow and the formation of annual rings.
The growth of the plant refers to its increase in dry mass and occurs at the plants two types of meristems: Apical Meristems and Lateral Meristems. Apical Meristems are found in the root and shoot tips which cause the lengthening and heightening of the plant of the plant (Primary Growth). This is done by elongation, vacuolation and differentiation of the meristematic cells. Lateral Meristems called cambium are found between the phloem and xylem of plants in the vascular bundle. They result in the thickening of the plant (Secondary Growth) and this is done by differentiation. Thick xylem vessels are found in the spring and thinner ones in the autumn. As a result annual rings form which can be used to determine the age of a tree.
Essay 19: Describe the Jacob-Monod hypothesis of gene action and how lactose is metabolised in E.Coli.
Jacob and Monod determined how beeta-galactosidase was produced and controlled in E.Coli by switching on and off genes when they were and weren't required. They suggested that an operon controls the related genes. Lactose is broken down by beeta-galactosidase to glucose and galactose, so they worked out that beeta-galactosidase was only produced when it was need (when lactose is present). When lactose (the inducer) is absent the reglator gene produces repressor molecule and binds with operator gene. Operator gene isn't free and so structural gene is switched off and no beeta galactosidase is produced and bacteria saves resources. However, when lactose is present it binds to the repressor molecule instead, leaving the operator gene free, and in turn allows beeta galactosidase to be produced.
Essay 20: Give an account of the control of growth and development in plants under the following headings: 1. Indole Acetic Acid (IAA) and Gibberellic Acid (GA).
IAA
IAA is produced in the root and shoot tips of the apical meristems and promotes cell elongation. However, root and shoot growth can be inhibited if IAA concentrations are too high. Apical buds produced large amounts of IAA which are transported fown to the lateral buds where growth is inhibited. This causes apical dominance. IAA is also responsible for leaf/fruit abcission. A decrease in IAA production (at the end of the growing season or after fruit formation) will cause an abcission layer to form before the leaf/fruit falls off.
GA
GA also promotes cell elongation and cause internodes in the stem to grow which causes large amount of growth in drawrf plants. GA also helps to overcome bad see dormancy. GA induces a-amalyase production during germination. The GA produced by the seed embryo passes to the aleurone layer where GA stimulates the aleurone layer to produce a-amalyase. A-amalyase then breaks down starch into maltose which is the sugar used for energy in germination at the food store/endosperm which requires it.
Essay 21: Write notes on the importance of iron, calcium and vitamin D in animals.
Iron, calcium and vitamin D are essential for growth and development. Iron is needed in small amounts (14 mg) each day. Women need it more than men due to blood loss through pregnancy and menstruation. It's other uses include transport of oxygen around the body by hamoeglobin and being part of enzymes and hydrogen carriers. Defiency leads to headaches, fatigue and anaemia. Iron can be found in meta, green vegetables and cereals. Calcium is required in larger amounts (800 mg) each day. Calcium makes strong bones and teeth and helps muscle contraction and is also involved in blood clotting. Defiency leads to blood clotting problems and weak bones. Can be found in dairy products and green vegetables. Vitamin D is needed to help calcium absorbption in the intestines and can be found from sunlight and foods such as milk and egg yolks. A defiency leads to rickets.
Essay 22: Discuss the effect alchohol, nichotine and thalidomide can have on foetal development as well as the effect lead can have on a human.
A foetus depends on its nutrients from its mother in order to grow. The nutrients diffuse from the mothers bloodstream to the baby's through placenta. Drugs and Chemicals can also pass through by this means. Alchohol and Nicotine can cause mental retardation and retarded growth. Thalidomide can cause limb deformities.
Lead is another chemical that can cause harm in humans, although it happens after birth rather during foetal development. Lead inhibits certain metabolic pathways which causes mental retardation and/or learning difficulties. Symptomns of it can includew vomitting, headaches, clumsiness and irritability.
Essay 23: Describe the effects of light on plants and animals.
Plants
Lights effect on plants can be split up into three parts: photoropism, etiolation and short/long day plant. Photoropism causes plants to grow towards the light. Light destroys IAA, so the side of a plant which is in the shade will have more IAA and the side in sunlight will have less. There is faster growth in the shaded side so this side will bend towards the light. Plant growth in the absence of light is also called etiolation. An etiolated plant will have small chlorotic leaves, long internodes and a weak stem. Since the plant is tall, it increases its chance of light for photosynthesis. Plants also show responses to daylengths which is called photoperiodism. Photoperiod refers to the hours of light during a day. Long day plants are plants that flower when photoperiod is more than a critical level and they usually flower in spring/early summer. Short day plants are plants that flower when the photoperiod is less than a critical level and they usually flower in late summer/autumn.
Animals
Animals can be split up into short day breeders and long day breeders. Increasing photoperiod will stimulate reproductive activity in long day breeders such as rabbits and birds which mate in spring. Decreasing Photoperiod helps reproductive behaviour in short day breeders such as sheep and deer which mate in autumm.
Essay 24: Give an account of how the glucose concentrations, water concentrations and body temperature are regulated in the body.
Negative Feedback
Negative Feedback is the generalised way in which the body detects a change in it's internal environment, and through receptors, finds away to correct it.
Glucose Concentration
Cells are always using glucose to provide the body with energy and it is gained through food. When glucose is absorbed blood sugar/glucose concentration rises. Glucose can be stored and broken down when required and is stored as glycogen in the liver. Two hormones are involved: Insulin activates the enzyme that stores glucose as glycogen and glucagon which activates the enzyme that breaks down glycogen to glucose. Receptor cells are used to determine whether insulin or glucagon needs be produced (by the pancreas). Adrenaline can breakdown glycogen to glucose in emergencies.
Water Concentration
This is the maintenance of water and salts at correct levels. An increase in water concentration is caused by drinking too much water whereas a decrease is caused by sweating/not drinking enough. ADH is the hormone which is used to control water concentration. It is produced by the pituatary glands. Osmoreceptors found in the hypothalamus detect the change and stimulates ADH secretion. If water concentration is too high then ADH production is less which decreases the permeability of the kidney tubules so kidneys do not reabsorb water and large volume of dilute urine is produced. If water concentration is too low then ADH production is high which increases the permeability of the kidney tubules and so a small amount of concentrated urine is produced.
Body Temperature
Body temperature is normally 37 degrees celsuis internally and 33 degrees celsuis on the surface. A rise in body temperature is detected by thermoreceptors in the hypothalamus which causes a number of different responses: vasodilation, hairs don't rise, increased sweating, no shivering. A drop in body temperature is detected by thermoreceptors in the hypothalamus which causes a number of different responses: vasoconstriction, hairs do rise, decreased sweating, shivering.
Essay 25: Give an account of the regulation of animal and plant populations by environmental factors.
A population is a group of animals or plants of the same species occupying a habitat. Within an ecosystem, the size of a population remains fairly stable/constant, despite a few short term fluctuations. The density of a population is basically how many individuals live in a particular area. There are two types of factors which affect a populations size: density independent factors and density dependent factors. Density independent factors such as drought and forest fire are not affected by the density of the population. For example, a drought will affect a population the same no matter how many organisms live there. Density dependent factors increase as the population density increases. Factors include disease, food supply and predation. For example, a predator is more likely to target large, dense populations, so if a population is dense predation will increase, hence density dependent.
Essay 26: Using examples, explain why populations needs to be monitored.
People can find out a great deal of things by monitoring populations so it is no wonder such an emphasis is put on doing so. Species that provide us with raw materials are monitored to ensure they do not run out. For example, fish stocks in the north sea started to decrease so the government introduced quotas. Pest species are also controlled to avoid spread of disease. For example, locusts and rats. Another reason for monitoring population is to see levels of pollution. For example, lichens can detect levels of pollutions in certain areas. And finally, to allow protection of endangered species. For example, panda populations are monitored to ensure they continue to live.
Essay 27: Give an account of succession in plant communities.
Plant Succession is the change in plant types/species over a certain time. Plant Succession is uni directional. For example as you move further inland from the beach. The pioneer community is the stage of plant succession where the species of plant first colonise an area and they are usually able to withstand unfavourable conditions. These pioneer plants will eventually decompose and improve the soil fertility, depth, pH, etc. This results in the intermediate community. There is an increase in shade and shelter which promotes the growth of different plants. Plants here have deeper roots and are taller. Soil fertility and depth continues to increase and eventually the soil is suitable for trees. A wide variety of trees begin to grow and mixed woodland forms. This is known as the climax community. Secondary succession begins on sites whre some organisms have survived. This site will have existing soil and some organic material present. E.g. forest destroyed by fire.
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I have also started filling them in. -
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Re: higher biologyYeah I never even had a seat :P I sat on the bench around the class xD For Essays in Unit 3 (like on temperature regulation) I always forget about negative feedback and I lose like 3-4 marks because of it(Original post by Imfeelingthis)
Aahh that happened with us for english.. We went 4 weeks without an English teacher hmm parts of unit 3 is a bit of common sense really I think
Last edited by TheFOMaster; 17-05-2012 at 19:37. -
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Re: higher biologyI can't even remember my name half of the time let alone essays(Original post by Bonzo10)
My revision for my prelim in March consisted SOLELY of learning essays from the past papers. I got a really high grade. Essays are the key people. Learn them!
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Re: higher biologyI don't like any of the regulation stuff D:(Original post by TheFOMaster)
Yeah I never even had a seat :P I sat on the bench around the class xD For Essays in Unit 3 (like on temperature regulation) I always forget about negative feedback and I lose like 3-4 marks because of it
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Re: higher biologyAha well what can I say... One does try xD(Original post by Bonzo10)
Hahaha I chuckled at this. Just re-write the same essay over and over and over. You'll all do great!
